Raw, warm-water shrimp, particularly those species from such families as Penaeidae and Sicyoniidae, which are found in tropical and semi-tropical waters, are especially difficult to peel because their excessive sliminess makes them difficult to grasp in the peeling nips of conventional automatic shrimp-peeling machines. In such conventional machines, peeling nips are formed by a power roller and a smaller diameter insert roller frictionally driven by the power roller.
Precooking shrimp coagulates the slime, making them less slippery. Precooking prior to peeling using insert rollers having a diameter as small as 1.1 cm (7/16 inch), is practiced with cold-water varieties of shrimp, and is disclosed in U.S. Pat. No. 3,276,878, James M. Lapeyre, issued Oct. 4, 1966. Such precooking, however, is not practiced with warm-water shrimp for two reasons. First, in many instances, the desired end product is raw, peeled shrimp. Second, because of biological differences between warm- and cold-water shrimp, cooking warm-water shrimp prior to peeling makes them more difficult to peel than if left uncooked.
To improve the grasp of the peeling nip of the rollers on raw, warm-water shrimp, knurled insert rollers, such as those disclosed in U.S. Pat. No. 3,704,484, James M. Lapeyre and Robert F. Couret, issued Dec. 5, 1972, have been used. The spiral knife-edge knurling improves the grasp of the rollers on the shrimp to increase the speed of the peeling. Knurled insert rollers with a relatively wide diameter of 1.43 cm (9/16 inch) have been the industry standard for peeling raw, warm-water shrimp. Unfortunately, the knurling and the tight nip treat the shrimp meat harshly, resulting in the loss of edible meat. Furthermore, the harsh treatment tends to scar the shrimp meat, detracting from its appearance and, hence, its value.
Therefore, an object of the invention is to increase the yield and quality of uncooked shrimp meat peeled by shrimp peeling machines. Advantages, features, and other objects of the invention will be found throughout the following specification, claims, and drawing.